Dear Sarah,

yes you have to have electrical isolation between the screws and the electrodes of the cell. The normal practice is to put a mica washer between the metallic electrode surface and the nuts of the screw and to make the hole of the screw larger then its diameter. An other solution is to use plastic screws if they are strong enough.

So, the ohmmeter must indicate open loop OL.

However the presence pf large resistance may not act as an effective short circuit between the screw and the metallic plate. But it is a correct practice to isolate the screw from the electrodes.

wish you success

Dear Sarah,

the screws will be isolated. The resistance you are measuring is most likely from the product water or eventually liquid coolant that is in effect like a resistor parallel to the plates: values beyond 50 kΩ are normally considered 'ok' though one usually tries to get higher resistance.

Regards